const manager =  function(process){
  var t = this;
  async function exitHandler(options, exitCode) {
    t.shutdown().then(()=>{
      setTimeout(function() {
        process.exit();
      }, 1000);
    }).catch(()=>{
      setTimeout(function() {
        process.exit();
      }, 10000);
    });
  }
  [`SIGINT`, `SIGUSR1`, `SIGUSR2`,`SIGTERM`].forEach((eventType) => {
    process.on(eventType, exitHandler.bind(null, eventType));
  });

  var shutdownTasks = []

  t.addShutdownTask = function(task,maxDuration=5000){
    shutdownTasks.push({t:task,d:maxDuration});
  };

  t.shutdown = function(){
    return new Promise((res,rej)=>{
      console.log("Shuting down ...");

      var maxDuration = 1000;
      var running = 0;
      var timeout = null;

      function mayShutdown(force=false){
        if(running==0||force){
          if(timeout!=null)clearInterval(timeout);
          res();
        }
      }
      running++;
      for (var i = 0; i < shutdownTasks.length; i++) {
        try {
          if(shutdownTasks[i].d>maxDuration)maxDuration=shutdownTasks[i].d;
          running++;
          let a = shutdownTasks[i].t();
          if(typeof a.then == "function"){
            a.then(()=>{
              running--;
              mayShutdown();
            });
          }else{
            running--;
            if(shutdownTasks.length-1 == i){
              mayShutdown();
            }
          }
        } catch (e) {
          running--;
          mayShutdown();
        }
      }
      running--;
      timeout = setTimeout(function () {
        timeout = null;
        mayShutdown(true);
      }, maxDuration);
      mayShutdown();
    });
  };
  t.saveShutdown = function(){
    t.shutdown().then(() => {
      setTimeout(function() { //some save time
        process.exit();
      }, 1000);
    }).catch(() => {
      setTimeout(function() { //shutdown on error with more save time
        process.exit();
      }, 10000);
    });
  }
}
export default manager;